Dynamic Analsis Of A New Ultrasonic Drilling

Based on the mechanism that transmission of the mechanical vibration is vertical in the metal, the ultrasonic drilling equipment can realize the impact to the hole. Compared with the traditional drilling equipment, it has many characteristics such as no axial force, low power consumption, so different holes machining can be achieved, and it also has some significant advantages in hard brittle materials processing holes. By using the principle of the piezoelectric driving, this new drilling has the same advantages as the traditional ultrasonic drilling such as simple structure, small size, light weight and low power consumption. At the same time, a free-mass is added in this system to achieve the energy coupling which ultrasonic energy to acoustic energy, amplitude of the dill can be enlarged and the drilling rate can be improved significantly. In order to get the principles of the energy coupling and kinematics and dynamics of the collision process, the following research has been done:The working principle of the new ultrasonic drilling and the design theory of the size parameters of each part are introduced. Based on the past experiments, the various parts of the system have been selected. Connection method beneficial to the vibration transmission is determined. Depending on the one-dimensional vertical vibration theory, the sizes of each part of the transducer, horn and drill, which are beneficial to the amplitude amplifying, are calculated. This new drilling device has been designed.By analyzing the collision process of the portion of energy coupling that ultrasonic to acoustic, a simple model of the free-mass has been established. Based on the real impact of the free-mass, horn and drill, a more real model which called time-discrete modeling has been established. This model gets the parameters of the impact by using the previous parameters of the impact, which is an iterative solution process. By using Newton’s method of Motion, the movement of the free mass and drill can be deduced. By giving the right initial parameters of ultrasonic drilling, the trajectory of the free-mass is extracted.According to the Newton’s method, the vibration system of the ultrasonic can be abstracted to a mass-spring-damper system so that the impact of the free mass can be added to the vibration system. By analyzing the stress of the whole system, the energy coupling portion is abstracted to a mass-spring-damper system also. By using the mechanical dynamics analysis software ADAMS, the impacts of the coupling portion are simulated, and the quality of the free-mass is analyzed by extracting the displacement and spectrum analysis of the freemass’ s motion.In order to research how the free mass impacts the ultrasonic drill drilling rate, numerical simulations of impact between the drill stem and worked medium have been done by using the display algorithm of ANSYS/LS-dyna. By analyzing and comparing stress distribution of drilling interface during the drilling process, the influence of the quality and the free-space of free mass on the ultrasonic-drill drilling rate with different free masses, and the influence of the power of ultrasonic drilling on the limitation of quality of the free mass are gotten.According to the working principle of ultrasonic vibration system and previous design and calculation of the new ultrasonic drilling, a prototype has been tested. The vibration frequency and the influence of the free-mass to the drilling rate are tested. Simulation results are consistent with the analysis which confirmed the mechanism of the energy coupling and amplifying of amplitude.